Four spellings of the comparative form of "frothy" are given. Select the correctly spelt word.

Introduction / Context:
Spelling questions often focus on comparative and superlative forms of adjectives, where extra letters or doubled consonants can confuse students. Here, you must pick the correct spelling of the superlative form of "frothy". "Frothy" describes something full of bubbles, such as foam on a drink or waves. The correct superlative is "frothiest". The other options contain either unnecessary extra letters or incorrect vowel patterns.

Given Data / Assumptions:
- The base adjective is "frothy".
- We are looking for the superlative form (the most frothy).
- Options are "frothyest", "frothiest", "frrothiest", and "frrothyest".
- Standard English spelling rules for adjectives ending in "y" apply here.

Concept / Approach:
For adjectives ending in consonant + y (for example "happy", "busy", "frothy"), the comparative and superlative forms replace the "y" with "i" and add "er" or "est": "happy" becomes "happier" and "happiest"; "frothy" becomes "frothier" and "frothiest". Therefore, "frothiest" is the correct superlative form. The other options either keep the "y" or add extra consonants, which conflicts with standard spelling rules.

Step-by-Step Solution:
Step 1: Identify the pattern: frothy = frothi + est (replace y with i and add est). Step 2: Check "frothyest". It keeps the "y" and adds "est", violating the y to i change rule. Step 3: Check "frothiest". It replaces "y" with "i" and adds "est", exactly matching the rule. Step 4: Check "frrothiest" and "frrothyest". Both contain an extra "r" at the beginning, which is not present in the base word "frothy". Step 5: Conclude that "frothiest" is the only correct spelling.

Verification / Alternative check:
You can cross check with similar words: "healthy" to "healthiest", "cloudy" to "cloudiest". In all cases, the "y" changes to "i" before adding "est". Applying this pattern to "frothy" gives "frothiest". Any version that keeps "yest" or adds extra letters is almost always incorrect in formal English spelling.

Why Other Options Are Wrong:
- "frothyest": Incorrect because it keeps the "y" instead of converting it to "i".
- "frrothiest": Incorrect due to the extra "r", which does not exist in the base word.
- "frrothyest": Contains both the extra "r" and the wrong "yest" ending.

Common Pitfalls:
Candidates sometimes rely on how a word sounds rather than on spelling rules. English often uses patterns such as y to i changes in comparative and superlative adjectives. Learning and recalling these patterns reduces confusion in questions like this. Also, be careful not to accept options with accidental double consonants that do not exist in the base form.

Final Answer:
The correctly spelt word is frothiest.